notification: Remove old setter methods of MessageTray.Notification

We now have nice GObject properties for the properties that can be set
with in different ways, since we already changing the API so much let's
drop the old setter methods.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3173>

js/ui/messageTray.js

@@ -494,26 +494,6 @@ export class Notification extends GObject.Object {
         this._actions = [];
     }
 
-    setUrgency(urgency) {
-        this.urgency = urgency;
-    }
-
-    setResident(resident) {
-        this.resident = resident;
-    }
-
-    setTransient(isTransient) {
-        this.isTransient = isTransient;
-    }
-
-    setForFeedback(forFeedback) {
-        this.forFeedback = forFeedback;
-    }
-
-    setPrivacyScope(privacyScope) {
-        this.privacyScope = privacyScope;
-    }
-
     playSound() {
         if (this._soundPlayed)
             return;